A roller cone drill bit is one type of drill bit used to form wellbores in subterranean formations. A roller cone drill bit generally includes at least one support arm, and often includes up to three support arms. A respective cone assembly may be rotatably mounted on the interior portions of each support arm and may rotate around the interior portions of the support arm.
Each cone assembly often includes a base with a cavity or opening formed therein. Each cone cavity may be sized to receive exterior portions of an associated journal or spindle to allow rotation of the cone assembly relative to the associated journal or spindle during a subterranean operation. A wide variety of bearings, bearing assemblies, bearing surfaces, seals, and/or other supporting structures may be disposed between interior portions of each cone assembly and exterior portions of the associated journal or spindle.
Roller cone drill bits often include lubricant systems to supply lubricant to the journals, bearings, bearing assemblies, bearing surfaces, seals, and/or other supporting structures associated with rotation of each cone assembly mounted on a respective support arm. A variety of lubricants may be used with roller cone drill bits to accommodate the rotation of each cone assembly relative to the respective spindle. A wide variety of seals and seal assemblies may be used to block communication between downhole wellbore fluids (e.g., drilling fluids and/or hydrocarbons) and lubricants associated with the rotation of each cone assembly. Various types of systems have been used to maintain lubricant system pressure to minimize potential damage to bearings, bearing assemblies, seals, journals, and other supporting structures associated with rotation of a cone assembly relative to an associated support arm.